Antibiotics and resistance against them are natural defence mechanisms found in microorganisms. Medicine was revolutionized by the discovery of antibiotics. Extensive use of antibiotics and resulting selection pressures have led to increasing numbers of antibiotic resistant pathogens. Antibiotic resistance genes are an important tool for genetic engineering to select for transformed cells.

Antibiotic resistance is a huge problem for modern agriculture. Monocultures are highly susceptible to parasites. In the short term, antibiotics can be used to significantly increase production. However, over time, resistant strains will arise and antibiotics will become ineffective. Accordingly, antibiotics will also be ineffective against pathogens that infect humans.